Polyamide imide enamels insulation

Polyamide Imide Enamels. Aromatic polyamide imide insulations are made from aromatic acids and aromatic diamines. The polyamide imide polymers are primarily present in the form of polyamic acids in the Af-methyIpyrrolidone solutions. During the enameling process the polyamic acids undergo imidization and become essentially fully imidized. Whereas the polyester and polyester imide enamels contain cresylic acids as the major solvent, the polyamide imide enamels are mainly formulated with A/-methylpyrrolidone as solvent. 

These polyamide imide films have excellent thermal, mechanical, and electrical properties, and they are used to upgrade other enamel films. Other attractive features of polyamide imide film insulations are a low coefficient of friction and good solvent resistance. These enamels are rated for use at 200 °C. 

Dual Constructions. In addition to the "basic" magnet wire insulations in which the conductor wire is coated with a single enamel, there are a number of cases where two different enamels are used one overcoated over the other. Examples include polyurethane-base insulation overcoated with poly(vinyl butyral) or with nylon, or polyester-base insulation overcoated with nylon or with polyamide imide. 

S. Kbnig, K. W. Lienert, and G. Schmidt. Polyamide-imide resin solution and the use thereof for producing wire enamels. US Patent 7 122 244, assigned to Altana Electrical Insulation GmbH (Wesel, DE), October 17,2006. 

Also in this time frame, wire insulation producers began producing polyamide-imides using lower-cost isocyanate chemistry. This technology largely supplanted the acid chloride route for the wire enamel market. 

---